In-situ stress determination of 3 km oil-gas deep hole and analysis of the tectonic stress field in the southern Guizhou

The magnitude and direction of stress are important basic data for unconventional oil and gas exploration and analysis of regional tectonic stress field. In order to find out the present stress state in southern Guizhou area, the authors applied the Anelastic Strain Recovery (ASR) method to obtain the in-situ stress state in Carboniferous Dawuba Formation of southern Guizhou Area (Qianziye-1 well) ranging from 2877 to 2985 m in depth. Based on the features of regional tectonic development in Qiannan depression, the authors investigated the characteristics of regional tectonic stress field and the preservation conditions of oil and gas. The results show that the Carboniferous Dawuba Formation in southern Guizhou area gas retaining the normal fault stress regime, the orientation of maximum horizontal principal stress at the measuring point was in nearly SN direction, which was the same as the maximum principal stress direction of the paleotectonic stress field in the Yanshanian period. The late tectonic movements occurred mainly along faults, which suggests a relatively minor damage to the secondary oil and gas pools during the last phase of YanshanHimalayan movement. It is conducive to the preservation of oil and gas reservoirs in Qiannan depression.